The final four sketches, numbers 16 to 19, are typical of what one expects in the late afternoon and early evening of a convectively unstable day. The vigorous, sharp edged towers of cloud, delineating the updraughts, have largely dissipated, as the heating of the ground by the sun dies away. Instead, we see an extensive shield of rather uniform cirrus cloud, formed some 12-18 km above the ground as the updraughts spread out laterally when they meet the tropopause. This shield has some breaks in it. In number 18, we see the distant edge of the cirrus shield, with clear sky near the horizon. Fragments of the dissipating cumuliform clouds are still present below the cirrus shield, and this is what sketch 19 seems to be showing – Constable describes it as “all cloudy except a nascent opening at the top of the sky”. His final comment “the tint twice over” presumably refers to the differing colours of the fragments of low cloud and the extensive upper level cirrus cloud.